Question

find the equation of the tangent to the parabola x^2=16y at the point (4,1)

Answer 1

Differentiate both sides with respect to x, what do you get?

Answer 2

i got this so far,
y=x^2/16
dy/dx=2x/16
= x/8
at (4,1) dy/dx =4/8
=1/2

Answer 3

Yup!
So, slope of tangent = m = 1/2
Equation of tangent required is
y- y1 = m (x -x1)
(x1, y1) = (4,1)

Can you do it now?

Answer 4

yeah but i don't know hw i keep getting x-2y+4

Answer 5

the answer is x-2y-2=0

Answer 6

y- 1 = (1/2) (x -4)
Multiply both sides by 2
2 (y-1) = x-4
Can you continue??

Answer 7

yeah thanks !!

Answer 8

Welcome :)